You can use the rql search bar to either type RQL queries, plain text queries
or standard shortcuts such as <EntityType> or <EntityType> <attrname> <value>.

Ultimately, all queries are translated to rql since it’s the only
language understood on the server (data) side. To transform the user
query into RQL, CubicWeb uses the so-called magicsearch component,
defined in cubicweb.web.views.magicsearch, which in turn
delegates to a number of query preprocessor that are responsible of
interpreting the user query and generating corresponding RQL.